Turbine airfoil and method of controlling a temperature of a turbine airfoil

ABSTRACT

According to one aspect of the invention, a turbine airfoil includes a platform and a blade extending from the platform. The airfoil also includes a slot formed in a slashface of the platform, the slot being configured to receive a pressurized fluid via passages and configured to direct the pressurized fluid to a selected region of the turbine airfoil to improve airfoil life.

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates to turbines. Moreparticularly, the subject matter relates to an airfoil to be positionedin a turbine.

In a gas turbine engine, a combustor converts chemical energy of a fuelor an air-fuel mixture into thermal energy. The thermal energy isconveyed by a fluid, often air from a compressor, to a turbine where thethermal energy is converted to mechanical energy. Several factorsinfluence the efficiency of the conversion of thermal energy tomechanical energy. The factors may include blade passing frequencies,fuel supply fluctuations, fuel type and reactivity, combustor head-onvolume, fuel nozzle design, air-fuel profiles, flame shape, air-fuelmixing, flame holding, combustion temperature, turbine component design,hot-gas-path temperature dilution, and exhaust temperature. For example,high combustion temperatures in selected locations, such as thecombustor and turbine nozzle areas, may enable improved combustionefficiency and power production. In some cases, high temperatures incertain combustor and turbine regions may shorten the life and increasewear and tear of certain components. Accordingly, it is desirable tocontrol temperatures in the turbine to reduce wear and increase the lifeof turbine components.

BRIEF DESCRIPTION OF THE INVENTION

According to one aspect of the invention, a turbine airfoil includes aplatform and a blade extending from the platform. The airfoil alsoincludes a slot formed in a slashface of the platform, the slot beingconfigured to receive a pressurized fluid via passages and configured todirect the pressurized fluid to a selected region of the turbine airfoilto improve airfoil life.

According to another aspect of the invention, a method for cooling aturbine airfoil is provided, wherein the method includes flowing apressurized fluid into a passage formed in a platform of the turbineairfoil. The method also includes flowing the pressurized fluid from thepassage into a slot formed in a slashface of the platform, the slotbeing configured to direct the pressurized fluid to a selected region ofthe turbine airfoil to improve airfoil life.

These and other advantages and features will become more apparent fromthe following description taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWING

The subject matter, which is regarded as the invention, is particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The foregoing and other features, and advantages ofthe invention are apparent from the following detailed description takenin conjunction with the accompanying drawings in which:

FIG. 1 is a schematic drawing of an embodiment of a gas turbine engine,including a combustor, fuel nozzle, compressor and turbine;

FIG. 2 is a side view of an embodiment of an airfoil;

FIG. 3 is an end view of an embodiment of an assembly of airfoils;

FIG. 4 is a perspective view of another embodiment of an airfoil;

FIG. 5 is a detailed end view of an embodiment of an airfoil; and

FIG. 6 is a detailed end view of yet another embodiment of an airfoil.

The detailed description explains embodiments of the invention, togetherwith advantages and features, by way of example with reference to thedrawings.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a schematic diagram of an embodiment of a gas turbine system100. The system 100 includes a compressor 102, a combustor 104, aturbine 106, a shaft 108 and a fuel nozzle 110. In an embodiment, thesystem 100 may include a plurality of compressors 102, combustors 104,turbines 106, shafts 108 and fuel nozzles 110. As depicted, thecompressor 102 and turbine 106 are coupled by the shaft 108. The shaft108 may be a single shaft or a plurality of shaft segments coupledtogether to form shaft 108.

In an aspect, the combustor 104 uses liquid and/or gas fuel, such asnatural gas or a hydrogen rich synthetic gas, to run the turbine engine.For example, fuel nozzles 110 are in fluid communication with a fuelsupply and pressurized air from the compressor 102. The fuel nozzles 110create an air-fuel mix, and discharge the air-fuel mix into thecombustor 104, thereby causing a combustion that creates a hotpressurized exhaust gas. The combustor 104 directs the hot pressurizedexhaust gas through a transition piece into a turbine nozzle (or “stageone nozzle”), causing turbine 106 rotation as the gas exits the nozzleor vane and gets directed to the turbine bucket or blade. The rotationof turbine 106 causes the shaft 108 to rotate, thereby compressing theair as it flows into the compressor 102. In an embodiment, airfoils(also nozzles or buckets) are located in various portions of theturbine, such as in the compressor 102 or the turbine 106, where hot gasflow across the airfoils causes wear and thermal fatigue of turbineparts, due to non-uniform temperatures. Controlling the temperature ofparts of the turbine airfoil can reduce wear and enable highercombustion temperatures in the combustor, thereby improving performance.Controlling the temperature of regions of and proximate to parts, suchas airfoils, to improve component life is discussed in detail below withreference to FIGS. 2-6. Although the following discussion primarilyfocuses on gas turbines, the concepts discussed are not limited to gasturbines.

FIG. 2 is a side view of a portion of an exemplary airfoil 200. Theairfoil 200 includes a platform 202 and a blade 204 extending from theplatform 202. A lower portion 206 extends below the platform 202 and maybe used to secure the airfoil to a part of a rotor or stator, such as aturbine wheel. A slot 208 is formed in a slashface 210 of the platform202. The slashface 210 is a surface of the platform configured to beplaced adjacent to a similar surface, or slashface, of an adjacentairfoil. A plurality of passages 212 are located in the slot and areconfigured to communicate a fluid, such as a pressurized cooling fluidor pressurized temperature controlling fluid, into the slot 208.Embodiments of the slashface 210 may include a single passage 212 tocommunicate the fluid. In an embodiment, the slashface 210 is joined toan adjacent slashface and the pressurized fluid flows into the slot 208to form a fluid barrier configured to restrict fluid flow across theslashfaces. In addition, the flow of pressurized fluid along the slot208 provides a distributing cooling of the platform slashface 202,thereby reducing wear and thermal fatigue while also improving andextending airfoil life.

As depicted, a hot gas path 214 flows from a leading edge 216 to atrailing edge 218 of the blade 204. The pressurized fluid barrier formedwithin the slot 208 restricts flow of the hot gas across the slashface210 to a cavity 220 (also called a “shank cavity”) in the lower portion206. A recess 222 to receive a pin is located below the platform 202. Inembodiments, the pressurized fluid is also configured to cool the recess222 and pin region. By restricting the hot gas flow across the slashface210, the cooling fluid within the slot 208 reduces wear and tear on thelower portion 206. In an embodiment, the pressurized fluid ispressurized air used to cool selected portions of the airfoil 200,wherein passages are used to direct the cooling fluid to the selectedportions. Further, the passages may include passages 212, wherein thepressurized fluid is distributed by the slot 208 to cool the platform202. In the embodiment, the slot 208 comprises a substantiallysemicircular cross section geometry. As depicted, the pressurized fluidis configured to flow in the direction of the hot gas path 214 flow,wherein the fluid exits the open trailing edge side of the slot 208. Inother embodiments, both ends of the slot 208 may be closed. The slot 208with closed ends may be configured to direct the pressurized fluid toother regions of the airfoil 200. In embodiments, the slot 208 in theslashface 210 may also provide stress relief for high stress regions ofthe airfoil 200, such as the trailing edge 218 and platform 202, whereinthe slot 208 weakens the slashface to divert a load from the high stressregion. As depicted, the cross sectional geometry of the slot 208 is aportion of a circle, ellipse or oval. In other embodiments, the crosssectional geometry will include any suitable shape, such as triangles,rectangles or trapezoids. Further, the slot 208 may have a substantiallyuniform cross-section across the slashface 210. Other embodiments mayhave a variable cross-section for the slot 208, such as a slot 208 thatvaries in cross section shape or size along its length. For example, theslot 208 may have a decreasing cross-section size in one direction toforce flow out of the slot 208, or with increasing size to reduce flowvelocity at the slot exit. In another example, the slot 208 couldtransition from a shape optimized for heat transfer at one part of theslash face 210 to one that is optimized for stress relief at anotherpart of the slash face 210.

In aspects, turbine parts, including airfoils, are formed of stainlesssteel or an alloy, where the parts may experience thermal fatigue if notproperly cooled during engine operation. It should be noted that theapparatus and method for controlling temperature in turbine parts mayapply to cooling of turbine buckets, as shown in FIGS. 2-6, as well asnozzles, compressor vanes or any other airfoil or hot gas path componentwithin a turbine engine.

FIG. 3 is an end view of an exemplary assembly of an airfoil 300 andairfoil 200. The airfoil 300 is substantially similar to airfoil 200 andincludes a platform 302, a blade 304 and a lower portion 306. Theplatform 302 is part of the airfoil body and includes a slot 308 formedin a slashface 310. The slashfaces 210 and 310 are joined as theairfoils 200, 300 are assembled in a turbine, such as on a rotor orstator. The slots 208 and 308 form a cavity 312 that receives thepressurized fluid flow. The cavity 312 enables flow of the pressurizedfluid to control the temperature of the platforms 202 and 302. Further,the cooling fluid barrier is formed in the cavity 312 to restrict a hotgas flow 314 across the slashfaces 210 and 310. In the embodiment, theairfoils 200 and 300 include additional slots 316 and 318 formed inslashfaces 320 and 322, respectively. The slashfaces 320 and 322 may bejoined to slashfaces of adjacent airfoils. In an exemplary embodiment, apassage 324 (also referred to as “channel”) is located in the airfoil200 body and provides the pressurized fluid to the slot 208 and suppliescooling fluid flow into the slot 308 and a passage 326. Thus, the bodyof airfoil 200 may receive the pressurized fluid from a source andsupply the pressurized fluid to the airfoil 300 via passages 324 and326, thereby cooling selected regions of the airfoil 300.

FIG. 4 is a perspective view of a portion of an exemplary airfoil 400that includes a platform 402, a blade 404 and a lower portion 406. Theplatform 402 includes a slot 408 formed in a slashface 410 for receivingpressurized fluid from passages 412. The platform 402 also includesfeatures, such as notches 414, to flow the pressurized fluid along asurface 416 of the platform 402. Accordingly, the pressurized fluidflows 418 toward an open end of the slot 408 and through notches 414.The pressurized fluid in the slot 408 provides distributed cooling ofthe platform 402 and forms a barrier to restrict fluid flow across theslashface 410. By flowing the pressurized fluid through the notches 414and to selected regions, such as the surface 416, the slot 408 andnotches 414 reduce thermal fatigue and wear. The slot 408 may includeany suitable cooling features, such as the exemplary notches 414, whichutilize structures, geometries and/or passages to direct fluid flow ontoand/or through selected portions of the airfoil, such as the platform402. Accordingly, by directing fluid onto the surface 416 via thenotches 414, the temperature of the surface 416 region is controlled toreduce wear and thermal fatigue. In embodiments, cooling features mayinclude passages and/or notches configured to cool regions such as theblade 204, 304, 404 and/or lower portion 206, 306, 406.

FIGS. 5 and 6 are detailed end views of exemplary platforms 500 and 600utilizing different cross sectional geometries for slots 502 and 602,respectively. Exemplary geometries include semi-circles, ovals,trapezoids and rectangles. The slot 502 comprises a rectangular crosssectional geometry in a slashface 504, wherein the geometry isconfigured to provide flow of pressurized fluid to selected regions ofthe platform 500. Similarly, the slot 602 comprises a trapezoidal crosssectional geometry in a slashface 604. Thus, the cross sectionalgeometries of the slots 208, 308, 408, 502, 602 are configured toprovide cooling to selected portions of the airfoils and/or form fluidbarriers of selected volumes to restrict fluid flow. The slots may beformed by any suitable method, such as casting and/or machining theplatform. Further, the pressurized fluid may be provided from anexternal and dedicated source, such as a coolant tank, or may be coolair provided internally by other portions of the turbine. The slot andsuitable cross sectional geometry may be utilized for cooling anyturbine hot gas path component, wherein the slot provides cooling and orrestricts fluid flow for the component. In an embodiment, the slot isconfigured to direct the pressurized fluid to lower mixing loss regionsof the airfoil to improve aerodynamic performance. For example, thecooling fluid may be directed to an area of the airfoil that, when itencounters other fluid flow, such as hot gas, does not producesubstantial amounts of turbulence. In embodiments, the cooling fluid isdirected to regions of the airfoil to enable energy from the coolingfluid. Such regions may include regions proximate the throat of theairfoil.

While the invention has been described in detail in connection with onlya limited number of embodiments, it should be readily understood thatthe invention is not limited to such disclosed embodiments. Rather, theinvention can be modified to incorporate any number of variations,alterations, substitutions or equivalent arrangements not heretoforedescribed, but which are commensurate with the spirit and scope of theinvention. Additionally, while various embodiments of the invention havebeen described, it is to be understood that aspects of the invention mayinclude only some of the described embodiments. Accordingly, theinvention is not to be seen as limited by the foregoing description, butis only limited by the scope of the appended claims.

1. A turbine airfoil comprising: a platform; a blade extending from theplatform; and a slot formed in a slashface of the platform, the slotbeing configured to receive a pressurized fluid via passages andconfigured to direct the pressurized fluid to a selected region of theturbine airfoil improve airfoil life.
 2. The turbine airfoil of claim 1,wherein the slot is configured to direct the pressurized fluid to lowermixing loss regions to improve aerodynamic performance.
 3. The turbineairfoil of claim 1, wherein the blade is configured to extend into a hotgas path and the slot is configured to form a barrier with thepressurized fluid to restrict flow of hot gas across the slashface to ashank cavity.
 4. The turbine airfoil of claim 1, wherein the slot isconfigured to be joined to an adjacent slashface of an adjacent airfoil.5. The turbine airfoil of claim 4, wherein the adjacent slashfacecomprises an adjacent slot to receive the pressurized fluid from thepassages in the slashface.
 6. The turbine airfoil of claim 4, whereinthe passages in the slashface are configured to provide the pressurizedfluid to an adjacent airfoil via the adjacent slashface.
 7. The turbineairfoil of claim 6, wherein the adjacent slashface comprises an adjacentslot with a passage to receive the pressurized fluid.
 8. The turbineairfoil of claim 1, wherein the slot comprises one open end to allow thepressurized fluid to flow out from the turbine airfoil.
 9. The turbineairfoil of claim 1, wherein the slot comprises a cross sectionalgeometry of one selected from the group consisting of: a semicircle, atrapezoid and a rectangle.
 10. The turbine airfoil of claim 1,comprising features in the slashface to enable flow of the pressurizedfluid on an upper surface of the platform.
 11. A turbine componentassembly comprising: a first component with passages in a body of thefirst component for flow of pressurized fluid; a first slot formed in afirst slashface of the body of the first component, the first slot beingconfigured to receive the pressurized fluid via the passages; and asecond component with a second slashface on a body of the secondcomponent, wherein the first slot is configured to form a barrier withthe pressurized fluid to restrict fluid communication across the firstand second slashfaces.
 12. The assembly of claim 11, wherein the firstslot, when joined to the second slashface, is configured to form abarrier with the pressurized fluid to restrict flow of hot gas acrossthe first and second slashfaces to improve component life by controllinga temperature of at least one of the first and second components. 13.The assembly of claim 11, wherein the passage in the first slashface isconfigured to provide the pressurized fluid to the second component. 14.The assembly of claim 11, wherein the first component and secondcomponent each comprise an airfoil.
 15. The assembly of claim 14,wherein the second slashface comprises a second slot.
 16. The assemblyof claim 14, comprising a passage in the second slot to receive thepressurized fluid into passages within the second component.
 17. Amethod for controlling a temperature of a turbine airfoil, the methodcomprising: flowing a pressurized fluid into a passage formed in aplatform of the turbine airfoil; and flowing the pressurized fluid fromthe passage into a slot formed in a slashface of the platform, the slotbeing configured to direct the pressurized fluid to a selected region ofthe turbine airfoil to improve airfoil life.
 18. The method of claim 17,wherein flowing the pressurized fluid from the passage into the slotcomprises forming a barrier with the pressurized fluid to restrict flowof hot gas across the slashface.
 19. The method of claim 17, comprisingjoining the slot in the slashface to an adjacent slashface of anadjacent airfoil.
 20. The method of claim 19, wherein the adjacentslashface comprises an adjacent slot to receive the pressurized fluidfrom the passages in the slashface.